1. Field of the Invention
This invention relates to fluid solids systems involving the transport of fluidizable solid particle material in gasiform material as a suspension and affecting rapid separation thereof upon discharge from the transport zone.
2. Description of The Prior Art
The transport of fluidizable particle material from one zone to another as a suspension in gasiform material has been used for a great many years in many different industries. It has been particularly usefull in systems involving the upgrading of hydrocarbons and regeneration of solids, whether catalytic or inert, and used in hydrocarbon upgrading systems.
With the advent of high activity zeolite cracking catalyst for effecting upgrading of hydrocarbon feed by catalytic cracking it has become essential, to minimize overcracking, to effect the cracking operation in a riser contact zone or other form of restricted diameter transport zone providing and/or permitting control over the residence contact time therein between hydrocarbons and solids in the range of 0.5 up to about 10 seconds, but more usually less than about 3 or 4 seconds. During such a hydrocarbon upgrading operation, hydrocarbonaceous material, more often referred to as carbonaceous material or simply as coke, is deposited on the solid particle material. To restore the usefullness of the solid particle material, the deposited carbonaceous material is removed by combustion with oxygen containing gaseous material such as air, air enriched with oxygen and combustion product flue gases comprising or enriched with oxygen. Thus, it is imperative in any of these riser or confined transport operations to separate the suspension passed therethrough substantially immediately upon discharge therefrom. The urgency of rapidity of separation is particularly concerned when upgrading hydrocarbon feeds so that conversion thereof does not proceed beyond desired limits.
In the prior art hydrocarbon conversion systems, separation of the solid particle material from suspending gasiform material is most usually accomplished within a so called disengaging chamber or zone. The riser of transport zone may discharge within the disengaging chamber in coaxial alignment therewith or more than one riser contact zone may be discharged therein but displaced from coaxial alignment therewith. In a single riser system such as disclosed in U.S. Pat. No. 4,332,674 the disengaging chamber is a long cylindrical chamber of restricted diameter dimension to restrain any substantial accumulation of separated solid particle material therein.
Palmer etal U.S. Pat. No. 3,123,547 discloses as expanding riser tube of more restricted dimension at it's discharge end, discharging through slots in the wall of riser into a relatively large diameter disengaging vessel provided with cyclone separating means. The riser of this patent provides an annular stripping zone down through which separated solids are passed countercurrent to stripping gas charged to a bottom portion thereof.
Bowles U.S. Pat. No. 3,406,112 discloses an apparatus combination of coaxially aligned vessel comprising a lower regeneration vessel, an upper disengaging vessel, an annular stripping zone and a riser reaction zone extending from a bottom portion of said regeneration vessel or chamber upwardly for discharge from the top open end thereof into the disengaging vessel and above the annular stripping zone.
Haddad et al. U.S. Pat. No. 4,219,407 discloses a riser reactor arrangement discharging into a disengaging zone from radially extending arms representing inverted channels open on the bottom side thereof and curving downward at the outer extremity thereof. The solids thus separated from gasiform material is passed downwardly through restricted solids stripping zones before withdrawal from a bottom portion of the vessel. Gasiform material is withdrawn through cyclone separating means in the upper portion of the disengaging vessel.
Vermilion Jr. U.S. Pat. No. 4,064,038 discloses a side by side riser reactor-riser regeneration system wherein the suspension discharged from each riser is passed through an opening in the riser periphery by a confined passageway directly into a cyclone separation zone.
Heffley et al U.S. Pat. No. 4,173,527 discloses a riser system discharging after centrifugally spinning the rising suspension by stator blades into a larger diameter zone comprising a gasiform material outlet pipe of smaller diameter coaxially aligned with and above the riser outlet. The upflowing suspension separated substantially by the stator blades caused the concentration of catalyst particles to pass through an annular zone defined by the distance between the wall of the riser and the wall of the coaxially aligned gasiform material outlet conduit or pipe.
Gross et al U.S. Pat. No. 4, 035,284 discloses a side by side hydrocarbon conversion-catalyst regeneration operation employing riser contact zone discharging against plates positioned above the upper open end of the riser contact zones and the use of cyclone separation zones to recover separated gasiform material.
In all of the systems above identified, rapid and efficient separation of a discharged suspension is not necessarily achieved either because the separation arrangement does not provide for high efficiency, cyclone separation equipment are employed under less than the most efficient conditions and/or the disengaging zone becomes filled with many stages of cyclone separation in parallel and sequential arrangement requiring a large disengaging vessel. Thus, these prior art systems are both inefficient and uneconomical for use in modern day low solid particle inventory contact systems. The present invention is therefore concerned with improving upon the separating facilities of the prior art and particularly with improving the efficiency and economics of the separation system by simplifying the system and reducing use of expensive cyclone separating equipment.